echoism vs synecdoche

echoism

noun
  • The practice of creating words or language by imitating sounds from the environment. 

synecdoche

noun
  • A figure of speech that uses the name of a part of something to represent the whole, or the whole to represent a part. 

  • The use of this figure of speech. 

How often have the words echoism and synecdoche occurred in a corpus of books? (source: Google Ngram Viewer )